JP5619622B2 - Porous electrodes and related methods - Google Patents

Description

(Technical field)
The present invention generally relates to electrodes, electrochemical cells, and related methods.

(Background of the Invention)
A typical electrochemical cell has a cathode and an anode, which participate in electrochemical reactions during operation of the cell. The electrode can include an electroactive material, which can interact with one or more cell components to facilitate conduction of ions between the electrodes.

  Some electrodes are often formed by coating a conductive substrate (including a porous conductive substrate) with an electroactive material in the presence of a binder material, of the electroactive material above. Adhesion and adhesion to the electrode can be enhanced. However, current methods for manufacturing electrodes using binder materials generally cannot achieve high loading of electroactive materials without causing significant mechanical problems in the finished electrode. . For example, the conductive substrate can be coated using a slurry comprising an electroactive material and an insoluble binder material. The insoluble binder material can typically cause rapid slurry solidification and limit the amount of electroactive material loading achieved at the electrode. Instead, the soluble binder solution can stabilize the slurry and facilitate the coating process. However, some of the resulting electrode structures are often blocked by the deposited material, making it less accessible to electroactive species during operation of the cell. This can result in a cell with reduced rate capability and electroactive substance utilization.

  Therefore, an improved method is needed.

(Summary of the Invention)
The present invention provides a method for forming an electrode, the method comprising forming a filler material over a first portion of a porous material, wherein the porous material is carbon. Forming an electrode material on at least a second portion of the porous material, wherein the electrode material comprises an active electrode species and a binder material; and the filling Removing at least some of the material material from the porous material, thereby forming the electrode.

  The present invention also provides a method for forming an electrode, the method comprising: a porous material comprising carbon; a filler solution comprising a filler material; wherein the filler material is a first of the porous material. Contacting the first portion to form a coating to produce a first coated porous material; comprising the first coated porous material and an active electrode species and binder material; Contacting the electrode material with the electrode material such that the electrode material forms a coating on at least a second portion of the porous material to produce a second coated porous material; and the filler material Removing at least some of the second coated porous material, thereby forming the electrode.

The present invention also provides a method for forming an electrode comprising a porous material comprising carbon, an active electrode species, a fluid carrier, and an electrode material comprising at least 5% by weight of the binder material relative to the porous material. Contacting the electrode composition such that the electrode composition forms a coating on at least a portion of the porous material to produce a coated porous material; and at least some of the fluid carrier; From the coated porous material, thereby forming the electrode, wherein the electrode has an active electrode species loading of at least 1.6 mg / cm ² and a porosity of at least 50%. Including sex.

  The present invention also relates to an electrochemical cell comprising: a cathode; an anode; and an electrolyte in electrochemical communication between the cathode and the anode, the cathode comprising an active electrode species, a porous material comprising carbon, and A binder material, wherein the binder material is at least partially soluble in a fluid carrier that is not so soluble that the active electrode species and the porous material are appreciable, wherein the electrochemical material The cell has an active material capacitance of at least 60% of the theoretical capacitance of the active material.

The present invention also provides a method for forming an electrode, the method forming an electrochemically active electrode precursor comprising a carbon-based electrically conductive material and an active electrode species. And essentially uniformly removing material from the electrode precursor to form the electrode, whereby the carbon-based conductive material, the active electrode species, or both Increasing the surface area, wherein the surface area can be exposed to an electrolyte during use of the electrode.
For example, the present invention provides the following items.
(Item 1)
A method for forming an electrode comprising:
Forming a filler material on the first portion of the porous material, wherein the porous material comprises carbon;
Forming an electrode material on at least a second portion of the porous material, wherein the electrode material comprises an active electrode species and a binder material; and
Removing the filler material from the porous material, thereby forming the electrode;
Including the method.
(Item 2)
The binder material and the active electrode species are applied to the porous material from a mixture comprising the binder material, the active electrode species, and a fluid carrier, wherein the binder material is at least partially in the fluid carrier. Item 2. The method according to Item 1, wherein the method is soluble.
(Item 3)
Item 2. The method of item 1, wherein the filler material is a hydrophilic material and the binder material is soluble in a hydrophobic solvent.
(Item 4)
Item 2. The method of item 1, wherein the filler material is a hydrophobic material and the binder material is soluble in a hydrophilic solvent.
(Item 5)
The method of claim 1, wherein the binder material is provided in a solvent in which the binder material is substantially soluble.
(Item 6)
The method according to item 1, wherein the removing step includes a step of heating the porous substance.
(Item 7)
The method of item 1, further comprising treating at least a portion of the porous material prior to forming the filler material.
(Item 8)
8. The method of item 7, wherein the treating step further comprises forming a polymeric material on at least a portion of the porous material.
(Item 9)
9. The method of item 8, wherein the polymeric material is a poly (ethylene glycol) coating.
(Item 10)
The method of item 1, wherein the filler material is a solid.
(Item 11)
The method of item 1, wherein the filler material is a liquid.
(Item 12)
Item 2. The method of item 1, wherein the filler material is octane, ammonium carbonate, or ammonium bicarbonate.
(Item 13)
Item 2. The method of item 1, wherein the binder material is a polymer material.
(Item 14)
Item 2. The method of item 1, wherein the binder material is poly (ethylene-co-propylene-co-5-methylene-2-norbornene) (EPMN).
(Item 15)
Item 2. The method according to Item 1, wherein the active electrode species is sulfur.
(Item 16)
The electrode includes at least sulfur loading of 1.5 mg / cm ^2, The method of claim 15.
(Item 17)
The electrode includes at least sulfur loading of 2.5 mg / cm ^2, The method of claim 15.
(Item 18)
The electrode includes at least sulfur loading of 5.0 mg / cm ^2, The method of claim 15.
(Item 19)
A method for forming an electrode comprising:
A porous material comprising carbon and a filler solution comprising a filler material are contacted such that the filler material forms a coating on the first portion of the porous material, the first coated Producing a porous material;
The first coated porous material and an electrode material comprising an active electrode species and a binder material such that the electrode material forms a coating over at least a second portion of the porous material. Contacting to produce a second coated porous material; and
Removing at least some of the filler material from the second coated porous material, thereby forming the electrode;
Including the method.
(Item 20)
A method for forming an electrode comprising:
A porous material comprising carbon; and an active electrode species, a fluid carrier, and an electrode composition comprising at least 5% by weight of a binder material relative to the porous material, wherein the electrode composition comprises at least the porous material. Contacting to form a coating on a portion to produce a coated porous material; and
Removing at least some of the fluid carrier from the coated porous material, thereby forming the electrode, wherein the electrode has an active electrode species loading of at least 1.6 mg / cm ^2. And comprising at least 50% porosity
Including the method.
(Item 21)
21. A method according to item 20, wherein the electrode composition comprises at least 10% by weight of the binder material with respect to the porous material.
(Item 22)
21. The method of item 20, wherein the electrode composition comprises at least 15% by weight of the binder material relative to the porous material.
(Item 23)
21. The method of item 20, wherein the electrode composition comprises at least 20% by weight of the binder material relative to the porous material.
(Item 24)
21. The method of item 20, wherein the electrode composition comprises at least 25% by weight of the binder material relative to the porous material.
(Item 25)
21. A method according to item 20, wherein the electrode composition comprises at least 30% by weight of the binder material with respect to the porous material.
(Item 26)
21. A method according to item 20, wherein the fluid carrier is hydrophobic.
(Item 27)
21. A method according to item 20, wherein the fluid carrier is hydrophilic.
(Item 28)
21. A method according to item 20, wherein the fluid carrier is water.
(Item 29)
21. The method of item 20, wherein the binder material is a polymer material.
(Item 30)
21. A method according to item 20, wherein the binder material is poly (ethylene-co-propylene-co-5-methylene-2-norbornene) (EPMN).
(Item 31)
Item 21. The method of item 20, wherein the active electrode species is sulfur.
(Item 32)
The electrode includes at least sulfur loading of 1.5 mg / cm ^2, The method of claim 20.
(Item 33)
The electrode includes at least sulfur loading of 2.5 mg / cm ^2, The method of claim 20.
(Item 34)
The electrode includes at least sulfur loading of 5.0 mg / cm ^2, The method of claim 20.
(Item 35)
An electrochemical cell,
A cathode comprising an active electrode species, a porous material comprising carbon, and a binder material, wherein the binder material is a fluid in which the active electrode species and the porous material are not so soluble as to be evaluated. A cathode that is at least partially soluble in the carrier;
An anode; and
Electrolyte in electrochemical communication with the cathode and the anode
Including
Wherein the electrochemical cell has an active material capacitance of at least 60% of the theoretical capacitance of the active material.
(Item 36)
36. The electrochemical cell according to item 35, wherein the electrochemical cell has an active substance capacitance of at least 70% of the theoretical capacitance of the active substance.
(Item 37)
36. The electrochemical cell according to item 35, wherein the electrochemical cell has an active substance capacitance of at least 80% of the theoretical capacitance of the active substance.
(Item 38)
36. The electrochemical cell according to item 35, wherein the electrochemical cell has an active substance capacitance of at least 90% of the theoretical capacitance of the active substance.
(Item 39)
36. The electrochemical cell according to item 35, wherein the active electrode species is sulfur.
(Item 40)
The electrode includes at least sulfur loading of 1.5 mg / cm ^2, the electrochemical cell of claim 39.
(Item 41)
The electrode includes at least sulfur loading of 2.5 mg / cm ^2, the electrochemical cell of claim 39.
(Item 42)
The electrode includes at least sulfur loading of 5.0 mg / cm ^2, the electrochemical cell of claim 39.
(Item 43)
A method for forming an electrode comprising:
Forming an electrochemically active electrode precursor comprising a carbon-based conductive material and an active electrode species; and
Removing material substantially uniformly from the electrode precursor to form the electrode, thereby increasing the surface area of the carbon-based conductive material, the active electrode species, or both The surface area can be exposed to an electrolyte during use of the electrode;
Including the method.
(Item 44)
44. The method of item 43, wherein the electrode has a relative active material capacitance that is at least 60% of the active material theoretical capacitance.

FIG. 1 shows an electrochemical cell according to one embodiment of the present invention. FIG. 2 shows an example of a binder material according to one embodiment of the present invention. FIG. 3 shows a graph of the vapor pressure of ammonium bicarbonate as a function of temperature. FIG. 4 shows (a) the solubility of ammonium bicarbonate in water as a function of temperature, and (b) the thermal cycling graph of ammonium bicarbonate in water. FIG. 5 shows an Arrhenius plot of the vapor pressure of (a) hexane and (b) ammonium bicarbonate. FIG. 6 shows a plot of specific capacity as a function of cycle number for two electrochemical cells. FIG. 7 shows (a) an electrochemical cell prepared using octane as the liquid filler at a discharge current of 500 mA, (b) 2.2 A, and (c) 4.4 A, and (d) 500 mA. , (E) at a discharge current of 2.2 A and (f) 4.4 A, ratio as a function of cycle number for essentially the same electrochemical cell prepared without octane as the liquid filler A plot of capacitance is shown.

  Other aspects, embodiments and features of the invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings. The accompanying drawings are not intended to be drawn to scale. For purposes of clarity, not every component is shown as a number, and every component of each embodiment of the present invention is not shown, and the illustration is understood by those of ordinary skill in the art. It is not necessary to make it happen. All patent applications and patents incorporated herein by reference are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control.

(Detailed description of the invention)
The present invention relates to electrochemical cells, electrodes, and related methods.

In general, the present invention provides a removable filler material (e.g., during the manufacture of an electrochemical cell or component thereof) to produce an electrochemical device with improved cell performance and capacitance ratio (e.g., Use of sacrificial substances). For example, the present invention may provide an electrochemical cell that exhibits enhanced utilization of electroactive species and / or increased availability of electroactive species within the electrochemical cell during operation. In some cases, the present invention may provide electrodes that advantageously have both high loads of electroactive species (eg, greater than 1.5 mg / cm ² ) and good adhesion and adhesion properties. Some electrochemical cells (eg, rechargeable batteries) of the present invention may include a porous electrode that includes one or more electroactive materials (eg, electroactive sulfur-containing materials) and a binder material.

  One aspect of the present invention is the discovery that the use of filler materials (eg, sacrificial materials) in the manufacture of electrodes can provide several advantages. In some cases, incorporating a filler material within a substrate (eg, a porous carbon material), and then removing at least some of the filler material to expose a portion of the substrate, It may provide improved ease of use of the substrate surface area relative to other components of the cell. For example, the filler material can be used to maintain the porosity of the electrode material so that the electrolyte can contact an internal portion of the electrode (eg, porous) during cell operation. Another advantageous feature of the present invention is the improved availability / accessibility of the active electrode species while maintaining the high load of the active electrode species and the stability and good mechanical properties of the electrodes. Is the ability to achieve

  Although the present invention may find use later in various electrochemical devices, an example of one such device is provided in FIG. 1 for illustrative purposes only. In FIG. 1, a general embodiment of an electrochemical cell may include an electrolyte layer in contact with the cathode, the anode, and both electrodes. The components can be assembled such that the electrolyte is placed in a stacked arrangement between the cathode and anode. FIG. 1 illustrates the electrochemical cell of the present invention. In the illustrated embodiment, the cell 10 includes a cathode 30 that can be formed on a substantially planar surface of the substrate 20. A porous separator material 40 may be formed adjacent to the cathode 30 and deposited on the cathode 30. The anode layer 50 may be formed adjacent to the porous separator material 40 and may be in electrical communication with the cathode 30. The anode 50 can also be formed on an electrolyte layer disposed on the cathode 30. Of course, the orientation of the components can vary, for example, other implementations where the orientation of the layers varies such that the anode layer or the electrolyte layer is first formed on the substrate. It should be understood that a form exists. Optionally, additional layers (not shown) (eg, a multilayer structure that protects electroactive materials (eg, electrodes) from the electrolyte) can be obtained from US patent application Ser. No. 11 / 400,781 (April 6, 2006). It may exist as described in detail in the application, the title of the invention “Rechargeable Lithium / Water, Lithium / Air Batteries”, Affinito et al., Which is hereby incorporated by reference in its entirety. Furthermore, non-planar arrangements, arrangements having material properties different from those shown, and other alternative arrangements are useful in connection with the present invention. A typical electrochemical cell will of course also include a current collector, external circuitry, housing structure, and the like. Those skilled in the art are well aware that there are many arrangements that can be utilized with the general schematic arrangement shown in FIG. 1 and described herein.

  As described above, the filler material can be used in a manufacturing process to form components of an electrochemical cell (eg, an electrode). The term “filler material” as used herein refers to a mechanical process sequence in which a plurality of materials are processed to make a desired structure (eg, an electrochemical structure). A substance used as a placeholder or a sacrificial substance. Once the relevant material of the structure is formed, at least some of the filler material can be removed while other materials are in place, thereby creating the desired structure. In some embodiments, the use of the filler material during the manufacture of a porous electrode can advantageously maintain the porosity of the electrode. In some cases, the use of the filler material during the manufacture of the porous electrode also allows the active electrode to be formed on the outer surface of the porous electrode, rather than on the surface of the inner pores of the porous electrode. Increasing the amount of species can enhance the availability of the active electrode species during operation of the cell.

  Thus, in some embodiments, the present invention provides a method for forming an electrode. In some embodiments, the filler material can be formed on a first portion of a material (eg, a porous material) and the electrode material is formed on at least a second portion of the material. obtain. The electrode material can include an active electrode species and a binder material (eg, a soluble binder material). Then, subsequent removal of at least some of the filler material from the material can produce the desired electrode structure.

  In some cases, the method includes: coating at least a portion of a porous material (eg, a carbon-containing porous material) with a portion of the porous material surface coated with the filler material; And / or forming a filler material such that at least some of the pores are “filled” with the filler material. For example, the method includes contacting the porous material and a filler solution comprising a filler material such that the filler material forms a coating on the first portion of the porous material, Forming a formed porous material. The filler solution may include the filler material and at least one fluid carrier that is soluble to the extent that the filler material can be evaluated. Removing at least some of the fluid carrier, for example via evaporation or heating, can result in the formation of the filler material on the surface of the porous material. In some embodiments, the filler material is a solid. In some embodiments, the filler material is a fluid (eg, octane). Some examples of filler materials include, but are not limited to, ammonium bicarbonate and water. However, it should be understood that other filler materials may be used in the context of the present invention, as described more fully below.

  In some cases, the filler material is deposited within the interior portion of the porous material via temperature cycling of a material having a positive temperature solubility gradient (ie, a material having an increased solubility as the temperature increases). Can be made. In an exemplary embodiment, the filler material comprises the porous material and a filler solution comprising a filler material and a fluid carrier, wherein the filler material is substantially dissolved in the fluid carrier. It can be formed on the porous material by contacting at temperature. The temperature of the filler solution and / or porous material can be lowered to a second lower temperature that can cause the filler material to precipitate within the pores of the porous material. The process can be repeated (eg, cycled) until a sufficient amount of filler material is formed within the pores of the porous material.

  In some cases, the filler material can be constrained onto the porous material via various saturation methods. Here, the porous material may be exposed to filler material vapor. For example, an inert gas saturation method can be used, wherein the porous material is placed in a closed vessel where an inert dry gas (eg, nitrogen, argon) is purged at a measured flow rate. The flow of filler material in vapor form can be introduced into the vessel alone or in combination with a flow of inert gas. In some cases, a container containing small beads can be attached to flow to an inert gas line so that a small flow of filler material fluid (eg, octane) flows gently over the surface of the small beads. Can be done. The filler material fluid is then vaporized into the inert gas stream to form a saturated inert gas that contacts (eg, passes through) the carbon material and then exits the container. Can be done.

  The filler material is then formed on the porous substrate by alternately heating and cooling the filler material over several cycles as it contacts (eg, passes through) the porous material. obtain. In some cases, a vortex tube can be used to generate a heated inert gas. In some embodiments, an ambient saturation method may be used. Here, the porous material is placed in a closed container and suspended in the entire solution of filler material at the bottom of the container (eg, by wire cloth). Alternatively, the porous substrate can be saturated with a filler material using a ball mill jar. For example, the ball mill jar can be purged with a dry inert gas and the porous substrate can be added to the ball mill jar. Filler material vapor can be added and the porous substrate and filler material vapor can be mixed by inversion until well mixed. In some embodiments, the porous material can be dried before saturating.

  The filler material can be formed on the porous material in any amount suitable for a particular application. For example, in applications where it is desirable that the majority of the porous material be in contact with or in close proximity (eg, exposed) to other components of the cell (eg, electrolytes), the filler during manufacture may be The material can be formed on a relatively large portion of the porous material surface and later removed or partially removed to expose the desired amount of porous material. Alternatively, in applications where it is desirable that a small portion of the porous material is contacted or accessible to other components of the cell, during manufacture, the filler material may be deposited on the surface of the porous material. It can be formed on a relatively small part. In some cases, when forming the filler material on the porous material, the porous material is about 5-95% by weight relative to the porous material (eg, porous carbon material). A filler material may be included. In some cases, the porous material is about 15-85 wt%, 25-75 wt%, 35-65 wt%, or in some cases about 45-55 wt%, relative to the porous material. It may contain weight percent filler material. In one set of embodiments, the porous material may include about 50% by weight filler material relative to the porous material (eg, porous carbon material). The method of the present invention includes forming an electrode material or an electrode composition on at least a part of the porous material (including a part containing a filler material and / or a part not containing a filler material). obtain. In some cases, the porous material can be treated (eg, contacted, coated) with an electrode material comprising an active electrode species (eg, sulfur) and a binder material. Additional materials, fluid carriers, other additives, and / or combinations thereof can also be applied to the porous substrate in combination with the electrode material.

  In some cases, the binder material and the active electrode species are derived from a mixture (eg, electrode composition) comprising the binder material, the active electrode species, and at least one fluid carrier. Can be applied to. Removal (eg, evaporation or drying) of at least some of the fluid carrier can then form the electrode material on the surface of the porous material. In some cases, the mixture can be provided as a homogeneous solution, a heterogeneous dispersion, or a slurry. One skilled in the art can select the appropriate combination of binder material, active electrode species, and fluid carrier to produce the desired mixture. For example, a simple screening test can be performed by simply combining small amounts of the mixture components (eg, binder material, active electrode species, fluid carrier, etc.) to determine whether a solution or slurry is formed. Can be done. In some cases, the mixture can be further processed (eg, heated, stirred, sonicated, milled, etc.) before being applied to the porous substrate. The mixture can be processed to provide a uniform mixture, to prevent agglomeration, or to impart other desired characteristics to the mixture. In one embodiment, the mixture can be milled prior to application to the porous substrate.

  In some embodiments, the electrode composition, in some cases, is at least 5% by weight, at least 10% by weight, based on the active electrode species (eg, sulfur), the fluid carrier, and the porous material. At least 15%, at least 20%, at least 25%, at least 30%, or more binder material.

  As described herein, the use of a soluble binder material can simplify the coating process, allowing the use of increased amounts of active electrode material in the mixture, and reducing the load of electroactive species. An electrode having the same can be produced. In some embodiments, the binder material can be at least partially soluble in the fluid carrier of the electrode composition. In some cases, the binder material may be at least partially soluble in a fluid carrier where the active electrode species, porous material, and / or filler material is not soluble to the extent that it can be evaluated. In some cases, the mixture is a fluid in which the active electrode species, binder material, and the binder material are at least partially soluble and not so soluble that the active electrode species and the porous material can be evaluated. It may be a slurry containing a carrier.

In some cases, the electrode composition (eg, slurry) can advantageously include a high solids load relative to known methods. For example, using previous methods, application of a mixture containing a high solids load to a porous carbon substrate can result in undesirable absorption of the fluid carrier by the carbon substrate. This can destabilize the mixture and / or cause precipitation of the binder material within the mixture. However, using the method of the present invention, a mixture having a high solids load can be easily applied to a carbon substrate containing a filler material. In some cases, the filler material may block the pores of the porous carbon substrate and minimize or prevent absorption of the fluid carrier by the porous carbon substrate. In some embodiments, the electrode can include an active electrode seed load of at least 1.6 mg / cm ² . The term “active electrode species loading” or “electroactive species loading” refers to the amount of active electrode species that is formed or “loaded” on the electrode. In some embodiments, the mixture has a solids content (eg, active electrode species content) of at least 10%, at least 20%, at least 30%, at least 40%, or more. obtain. The mixture may also contain other additives such as plasticizers and / or crystallization modifiers. In some embodiments, the additive is compatible with other components of the slurry (eg, incompatible with the other components) so that the additive does not adversely affect the performance of the cell. Active, or miscible with it). Examples of additives include, but are not limited to, ethylene carbonate, propylene carbonate, polyethylene glycol and polypropylene glycol.

In some embodiments, at least a portion of the substrate (eg, porous material) is treated prior to forming the electrode material on the porous material to provide the filler material, active electrode. The affinity of the porous material for species, binder materials, or other components associated with the manufacturing process may be altered (eg, enhanced). For example, the porous material can be treated with a suitable chemical that alters the hydrophilicity, hydrophobicity, or other characteristics of the porous material. In some cases, the polymeric material is formed on the porous material, or a portion thereof, prior to forming the filler material on the porous material, the porous material and the filler. The interaction between substances can be enhanced. In some embodiments, the polymeric material can be poly (ethylene glycol), which can increase the affinity of the temperament for a hydrophilic filler material (eg, water). One skilled in the art can select suitable compounds that can impart the desired characteristics (eg, hydrophilicity, hydrophobicity) to the surface of the porous material. .
In some embodiments, the substrate can be treated to produce a substantially anhydrous or dry material. For example, an untreated porous carbon material can contain water in its pores, which impedes its performance and / or ability to be treated using the methods described herein. obtain. In some cases, it is desirable to remove water from the carbon material to provide a suitable surface on which a material (eg, filler material, binder material) can be formed. The water can be at least partially removed from the substrate using a variety of methods, including heated inert gas cycling or drying with a desiccant. Heated inert gas cycling typically involves placing the substrate in a sealed container through which an inert dry gas (eg, nitrogen, argon) is passed. The inert gas can be allowed to pass through the carbon material and then exit the container. The inert gas can be alternately heated or cooled over several cycles, thereby heating and cooling the substrate, and after the last cycle, the container is sealed under inert gas for storage Can be done. Drying with a desiccant involves placing the substrate in a desiccator containing water-absorbing beads to remove water vapor from the surface of the substrate. The filler material or a portion thereof can be removed from the porous material by various methods. For example, at least some of the filler material can be removed by heating the substrate. In other embodiments, the filler material may be at least partially removed by contacting (eg, rinsing) the substrate with a fluid carrier or other chemical. One skilled in the art can select a suitable method for removing a particular filler material. For example, filler material having a boiling point below the decomposition temperature of the other components of the electrode can be at least partially removed via heating. In another example, the filler material is a fluid that is not so soluble that other components of the electrode can be evaluated such that the filler material can be at least partially removed via rinsing with the fluid carrier. It can be substantially soluble in the carrier. The filler material can be removed at any time during or after the process, depending on the desired application. In some cases, the filler material can be removed from the porous material during formation of the electrode material.

  The filler material or part thereof then has a surface on which the resulting porous material contains electrode material (including active electrode species and binder material) located at a selected location, on the surface It may be selected to expose a portion of the underlying porous material to have the conductive substrate material exposed elsewhere. As described herein, the ability to selectively remove at least some of the filler material advantageously allows the porous material to be accessible to other components of the cell. While the amount of surface area can be increased, other materials of the electrode (eg, active electrode species, binder material) are maintained on or within the electrode surface.

  The amount of porous material surface area can be determined by the porosity of the electrode. That is, an increase in the porosity of the electrode can indicate an increase in the amount of porous material surface area of the electrode. In some embodiments, the electrode can have a porosity of at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or more. The porosity of the electrode can be determined using known methods (eg, BET measurements).

  In an exemplary embodiment, the porous carbon material can be treated (eg, coated) with poly (ethylene glycol) to increase the affinity of the porous carbon material for an aqueous fluid carrier. The porous carbon material can then be exposed (eg, contacted with water) to a liquid filler material (eg, water), which can fill at least some of the pores of the porous carbon material. . Next, a slurry containing electrode material in the presence of hexane as a fluid carrier can be applied to the porous carbon material. The electrode material may include sulfur as the active electrode species, and a polymer soluble binder (eg, poly (ethylene-co-propylene-co-5-methylene-2-norbornene)). The porous carbon material can then be heated at a first temperature to remove the hexane, resulting in the formation of the electrode material on the surface of the porous carbon material. Water (eg, a filler material) can then be removed by heating the porous carbon material at a higher second temperature to produce the electrode.

  In one set of embodiments, an electrochemically active electrode precursor can be provided, the electrode precursor comprising a carbon-based conductive material and an active electrode species. For example, the electrode precursor can include a porous carbon substrate and an active electrode species (eg, sulfur) formed on the substrate. Material can be removed essentially uniformly from the electrode precursor to form the electrode. As used herein, removing material “essentially uniformly” from the electrode precursor means that the material is uniformly removed throughout the bulk of the electrode precursor. For example, removing “essentially uniformly” material from the electrode precursor may not refer to removal of discrete portions of the electrode material, eg, via etching. In some cases, at least some filler material may be removed from the electrode precursor. The removal of the material can increase the surface area of the carbon-based conductive material exposed to or exposed to the electrolyte during use of the electrode, the active electrode species, or both. In some cases, removal of material from the electrode precursor may produce an electrode having a relative active material capacitance that is at least 60% of the active material theoretical capacitance.

The electrode can be prepared using the methods described herein and incorporated into an electrochemical device. Thus, some embodiments of the present invention also provide an electrochemical cell. The electrochemical cell can include a cathode, an anode, and an electrolyte in electrochemical communication with the cathode and the anode. In some embodiments, the cathode can include an active electrode species, a porous material including carbon, and a binder material (eg, a soluble binder material). In some cases, the cathode may include sulfur as the electrode active material. As described herein, electrodes made using the method of the present invention can have a high sulfur load relative to known cells. In some embodiments, the electrode is at least 1.5 mg / cm ² (eg, 1.6 mg / cm ² ), at least 2.5 mg / cm ² , at least 5.0 mg / cm ² , or in some cases And having a sulfur load higher than that.

In an exemplary embodiment, the electrode may have a sulfur load of 4.3 mg / cm ² and an electrode material thickness of about 190 microns.

In some embodiments, the electrochemical cell may exhibit a high active electrode species utilization, i.e., the electrode active material may be otherwise activated during operation so that cell performance is enhanced. Can be easily accessible and contacted with these components or species. In some cases, the active material capacitance may be at least 60%, at least 70%, at least 80%, or in some cases at least 90% of the active material theoretical capacitance. The “active material theoretical capacitance” for a particular material can be calculated using the following formula:
Q = 1/3600 × n × F / M
here:
Q = theoretical electric capacity Ah / g (ampere time / gram),
3600 = seconds per hour,
n = number of electrons involved in the electrochemical process per molecule of substance F = Faraday constant, 96485 C / mol, and M = molecular mass (g) of the substance.

  One skilled in the art calculates the active material theoretical capacitance and compares it to the experimental active material capacitance for a particular material, so that the experimental capacitance is at least 60 of the theoretical capacitance. It can be determined whether it is greater than or equal to%. A wide range of materials may be suitable for use as filler materials, as described herein. In some cases, the filler material can be selected to have an affinity for a particular substrate (eg, a carbon substrate). In some cases, the filler material selected to be stable during the formation of the electrode material (eg, does not decompose, does not tear into slices, does not react, does not dissolve, etc.) Can be easily decomposed in one or more gases or vapors to facilitate rapid and complete removal. One skilled in the art can identify and select materials that exhibit this behavior, for example, by considering the chemical structure, or the solubility, volatility, and / or vapor pressure of the filler material at a given temperature. In an exemplary embodiment, FIG. 3 shows a graph of ammonium bicarbonate vapor pressure as a function of temperature, indicating that it can be decomposed / removed at temperatures of about 50-60 ° C. or higher.

  In other embodiments, the filler material is selected to be substantially insoluble with respect to the electrode composition applied to the porous material during formation of the electrode material. A simple screening test can be used to determine whether the filler material is soluble or insoluble in a particular environment that is desirably maintained in the structure during processing. A simple test can be performed in a conventional laboratory environment and involves simply exposing the filler material to various candidate processing solvents to determine solubility. If a class of filler material is thus identified as potentially suitable for use in the present invention, individual members of that class are screened prior to use in the actual processing environment, Their effectiveness can be determined.

  The filler material can be either liquid, solid, or a combination thereof. Examples of suitable filler materials include organic and inorganic salts such as ammonium carbonate, ammonium bicarbonate, and azidocarbonamide, sodium bicarbonate, potassium bicarbonate, sodium carbonate and sodium borohydride. In one set of embodiments, the filler material is ammonium carbonate or ammonium bicarbonate.In some embodiments, the filler material is a liquid (eg, water or hydrocarbon (eg, octane). )).

  In some cases, the filler material may be combined with a fluid carrier to form a filler solution. This filler solution can be applied to the porous substrate. Suitable fluid carriers include aqueous fluid carriers, non-aqueous fluid carriers, and combinations thereof. One of ordinary skill in the art can select an appropriate fluid carrier to form a filler solution, and a simple screening test can facilitate the formation of the filler material on the surface of the porous material. Thus, it can be used to determine whether it is sufficiently soluble in the fluid carrier. For example, a small amount of the filler material can be combined with a series of fluid carriers to determine compatibility. In some embodiments, the fluid carrier can have a relatively low boiling point so that it can be removed at moderate temperatures, and can have a low vaporization enthalpy to provide a high drying rate. For example, the fluid carrier may have a boiling point of 100 ° C. or lower, 90 ° C. or lower, 80 ° C. or lower, or in some cases even lower.

  In some embodiments, fluid carriers suitable for use in the filler solution include halogenated hydrocarbons or partially halogenated hydrocarbons (eg, methylene chloride), hydrocarbons (eg, pentane or hexane). ), Aromatic compounds (for example, benzene, toluene, or xylene), alcohols (for example, methanol, ethanol, isopropanol), other aqueous solvents (for example, water), mixtures thereof, and the like.

  As described herein, “binder material” refers to any material that, when present in the electrode, can enhance adhesion and adhesion of the active electrode species to the electrode. In some cases, a combination of binder materials can be used. One of ordinary skill in the art, in combination with the methods described herein and other materials associated with the electrochemical cell, can select a suitable binder material suitable for use in the present invention. The binder material is compatible with (eg, inert to, the other components) other components of the cell, including but not limited to the cathode, anode, and electrolyte. Can be selected. For example, the electrochemical cell can include a polysulfide, and the binder material can react with the polysulfide within the cell during operation and the cell with a by-product that is formed substantially irreversibly. Certain functional groups that can be contaminated (eg, carbonyl groups (eg, esters, ketones, aldehydes, etc.)) may be selected. The binder material also exhibits good adhesion to the porous material (eg, porous carbon material) and / or may crack or tear into flakes during processing or while the cell is operating. You can choose not to. In some embodiments, a substantially non-toxic binder material can be used.

  In some cases, the binder material can be selected to be substantially insoluble in the electrolyte. That is, the binder material may not be dissolved by the electrolyte and / or may be so soluble that it can be evaluated with respect to the fluid carrier. The binder material can be provided in a solvent in which the binder material is substantially soluble. In some cases, the binder material can be substantially soluble in the non-aqueous fluid carrier. In some cases, the binder material can be substantially soluble in an aqueous fluid carrier.

  In some embodiments, the binder material can be a polymeric material. Examples of polymeric binder materials include polyvinylidene fluoride (PVDF) based polymers (eg, poly (vinylidene fluoride) (PVDF) and its copolymers and terpolymers with hexafluoroethylene), tetrafluoroethylene, chloro Trifluoroethylene, poly (vinyl fluoride), polytetraethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), polybutadiene, cyanoethyl cellulose, carboxymethyl cellulose, and blends thereof with styrene-butadiene rubber, polyacrylonitrile, ethylene Examples include, but are not limited to, propylene diene terpolymers, styrene-butadiene rubber (SBR), polyimides, or ethylene-vinyl acetate copolymers. No. In some cases, the binder material may be substantially soluble in an aqueous fluid carrier and may be cellulose derivatives (typically methylcellulose (MC), carboxymethylcellulose (CMC) and hydroxypropylmethylcellulose (HPMC). ), Polyvinyl alcohol (PVA), polyacrylate, polyacrylamide (PA), polyvinyl pyrrolidone (PVP) or polyethylene oxide (PEO), but are not limited thereto.

  In one set of embodiments, the binder material is poly (ethylene-co-propylene-co-5-methylene-2-norbornene) (EPMN). This can be chemically neutral (eg, inert) to the cell components (including polysulfides). FIG. 2 shows the chemical structure of EPMN. EPMN may also provide sufficient adhesion to, for example, porous carbon materials, or other substrate materials, including metal substrates (eg, aluminum).

  As described above, the binder material can be combined with a fluid carrier during the formation of the electrode material on the porous material in addition to other materials (eg, active electrode species). . In some cases, a fluid carrier that is miscible or soluble to the extent that the binder material can be evaluated can be used. In some embodiments, the fluid carrier may be selected such that the filler material is not miscible or soluble to the extent that it can be evaluated relative to the fluid carrier, resulting in formation on the porous material. The filler material that is applied remains substantially intact during the formation of the electrode material. In some embodiments, the fluid carrier can be selected such that the active electrode species is not miscible or soluble to the extent that it can be assessed relative to the fluid carrier. This can be advantageous in selectively placing the electrode material at specific locations on the porous material. For example, it may be desirable to form the electrode material primarily on the surface of the porous material to minimize or prevent formation within internal locations (eg, pores) of the porous material. Treating the porous material with an electrode composition comprising a binder material, an active electrode species, and a fluid carrier that is soluble to the extent that both the binder material and the active electrode species can be evaluated is the porous material Can cause undesirable deposition or crystallization of the active electrode species within the pores. However, treatment with an electrode composition comprising a binder material, an active electrode species, and a fluid carrier that is soluble to the extent that the binder material can be evaluated and is not soluble to the extent that the active electrode species can be evaluated can be treated with the porous material described above. Deposition of the active electrode species can occur mainly on the surface of the material. This can improve the utilization of the active electrode species during cell operation.

  In an exemplary embodiment, sulfur can be formed on a porous carbon substrate in the presence of water and a water soluble binder material, wherein the sulfur is not soluble to the extent that it can be evaluated in water. This can result in an electrode where a relatively high load of sulfur can be formed on the outer surface of the porous carbon material rather than inside the pores. This results in enhanced accessibility of the sulfur while the cell is operating.

  In some cases, the fluid carrier used during formation of the electrode material is a temperature at which the filler material can decompose to minimize or prevent premature removal of the filler material. It can be selected to exhibit a high evaporation rate at temperatures below. That is, the fluid carrier used during electrode material formation is such that the vapor pressure of the fluid carrier is higher than the vapor pressure of any decomposition products formed by the filler material within a set temperature range. Can be selected. For example, the fluid carrier may have a boiling point or vaporization enthalpy below the decomposition temperature, or the vaporization enthalpy of the filler material. This may allow removal of the fluid carrier to form the electrode material while minimizing or preventing premature removal of the filler material.

  Any fluid carrier may be suitable for use in the electrode composition, including an aqueous fluid carrier, a non-aqueous fluid carrier, or a combination thereof. Examples of fluid carriers that can be used in the process of the present invention include solvents (eg, benzene, p-cresol, toluene, xylene, diethyl ether, glycol monomethyl or dimethyl ether, petroleum ether, heptane, hexane, pentane, cyclohexane, methylene chloride. , Chloroform, carbon tetrachloride, dioxane, tetrahydrofuran (THF), methanol, ethanol, isopropanol, dimethyl sulfoxide, dimethylformamide, hexamethyl-phosphate triamide, water, ethyl acetate, acetone, pyridine, triethylamine, picoline, mixtures thereof, etc. One skilled in the art can select a suitable fluid carrier suitable for use in a particular application, for example, the fluid carrier has its volatile (eg, boiling point), Based on such miscibility with soluble or other materials, it may be selected.

  In an exemplary embodiment, a porous substrate can include ammonium bicarbonate as the filler material, and hexane as the electrode composition fluid carrier during formation of the electrode material on the porous material. Can be used. Hexane has a boiling point of 68.8 ° C. and a vaporization enthalpy of 330 J / g. FIG. 5 shows an Arrhenius plot for the vapor pressure of (a) hexane and (b) ammonium bicarbonate. As shown in FIG. 5, at temperatures below 50-60 ° C., the hexane vapor pressure exceeds that of ammonium bicarbonate. Thus, a porous material comprising ammonium bicarbonate as a filler material can be treated (eg, coated) with an electrode material in the presence of hexane, the hexane being removed at a temperature below about 50-60 ° C. The electrode material may be formed on the porous substrate while the filler material remains intact. Upon evaporation of the hexane and formation of the electrode material, the temperature can be raised above 60 ° C. to remove (eg, decompose) the ammonium bicarbonate, and to open the pores of the porous substrate. Can be exposed.

  As described herein, the filler material, binder material, fluid carrier, and other materials associated with the manufacturing process are based on properties such as solubility, vapor pressure, decomposition temperature, and the like. , May be selected to have a particular relationship with respect to each other. As a result, the manufacturing process can be performed to produce the desired electrochemical structure. That is, the filler material, binder material, and other materials are preferably removed during the manufacturing process while the desired material reduces or prevents degradation or undesirable loss of material. It can be selected such that it can be formed and / or maintained above.

  For example, a hydrophobic filler material can be used in combination with a hydrophilic binder material. In another example, a hydrophilic filler material can be used in combination with a hydrophobic binder material. Further, the binder and filler material may be one or more such that the filler material can be removed from the substrate (eg, electrode) after formation of the binder material on the substrate. In combination with other fluid carriers. In some embodiments, the filler material is a hydrophilic material and the binder material is soluble in a hydrophobic solvent. In some embodiments, the filler material is a hydrophobic material and the binder material is soluble in a hydrophilic solvent. In some cases, the filler material may exhibit some solubility in the filler fluid carrier and may be substantially insoluble in the binder fluid carrier. In some cases, the binder material may exhibit some solubility in the binder fluid carrier and may be substantially insoluble in the filler fluid carrier.

  As used herein, an “active electrode species” or “electroactive species” is a species associated with an electrode (eg, cathode, anode) that undergoes an electrochemical reaction during operation of the cell. Say. For example, the active electrode species can undergo oxidation or reduction during charging / discharging of the electrochemical cell.

  Electroactive materials suitable for use as the cathode active material in the cathode of the electrochemical cell of the present invention include electroactive transition metal chalcogenides, electroactive conducting polymers, electroactive sulfur-containing materials, and combinations thereof. However, it is not limited to these. As used herein, the term “chalcogenide” relates to a compound comprising one or more of the elements oxygen, sulfur, and selenium. Examples of suitable transition metal chalcogenides include Mn, V, Cr, Ti, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Examples include, but are not limited to, electroactive oxides, sulfides, and selenides of transition metals selected from the group consisting of Os and Ir. In one embodiment, the transition metal chalcogenide is selected from the group consisting of electroactive oxides of nickel, manganese, cobalt, and vanadium, and electroactive sulfides of iron. In one embodiment, the cathode comprises one or more of the following materials: manganese dioxide, iodine, silver chromate, silver oxide and vanadium pentoxide, copper oxide, copper oxyphosphate, lead sulfide, Iron sulfide, lead bismuthate, bismuth trioxide, cobalt dioxide, copper chloride, manganese dioxide, and carbon. In another embodiment, the cathode active layer comprises an electroactive conducting polymer. Examples of suitable electroactive conducting polymers include, but are not limited to, electroactive and conducting polymers selected from the group consisting of polypyrrole, polyaniline, polyphenylene, polythiophene, and polyacetylene. Examples of conductive polymers include polypyrrole, polyaniline, and polyacetylene.

  In some embodiments, electroactive materials for use as the cathode active material in the electrochemical cells described herein include electroactive sulfur-containing materials. “Electroactive sulfur-containing material” as used herein refers to a cathode active material containing element, sulfur, in any form, wherein the electrochemical activity is oxidation or reduction of sulfur atoms or sulfur moieties. Is included. The nature of the electroactive sulfur-containing material useful in the practice of the present invention can vary widely as is known in the art. For example, in one embodiment, the electroactive sulfur-containing material includes elemental sulfur. In another embodiment, the electroactive sulfur-containing material comprises a mixture of elemental sulfur and a sulfur-containing polymer. Accordingly, suitable electroactive sulfur-containing materials include, but are not limited to, the elemental sulfur and organic materials containing sulfur and carbon atoms, which may be polymers, It may not be so. Suitable organic materials include those further comprising heteroatoms, conductive polymer segments, composites and conductive polymers.

  Examples of sulfur-containing polymers include US Pat. Nos. 5,601,947 and 5,690,702 (Skotheim et al.); US Pat. Nos. 5,529,860 and 6,117,590 ( U.S. Pat. No. 6,201,100 (issued March 13, 2001 to Gorkovenko et al., The commonly assigned assignee), and those described in PCT Publication No. WO 99/33130. It is done. Other suitable electroactive sulfur-containing materials comprising polysulfide linkages are described in US Pat. No. 5,441,831 (Skotheim et al.); US Pat. No. 4,664,991 (Perichaud et al.), And US Pat. No. 5,723. , 230, 5,783,330, 5,792,575 and 5,882,819 (Naoi et al.). Still further examples of electroactive sulfur-containing materials include, for example, US Pat. No. 4,739,018 (Armand et al.); US Pat. Nos. 4,833,048 and 4,917,974 (both De Jonghe). Including disulfide groups as described in US Pat. Nos. 5,162,175 and 5,516,598 (both Visco et al.); And US Pat. No. 5,324,599 (Oyama et al.) Is mentioned.

  In one embodiment, the electroactive sulfur-containing material of the cathode active layer comprises greater than 50% by weight sulfur. In another embodiment, the electroactive sulfur-containing material comprises greater than 75 wt% sulfur. In yet another embodiment, the electroactive sulfur-containing material comprises greater than 90% by weight sulfur.

  The cathode active layer of the present invention is about 20-100% by weight (eg, as measured after a suitable amount of solvent is removed from the cathode active layer and / or after the layer is properly cured). Of electroactive cathode materials. In one embodiment, the amount of electroactive sulfur-containing material in the cathode active layer is in the range of 5-30% by weight of the cathode active layer. In another embodiment, the amount of electroactive sulfur-containing material in the cathode active layer is in the range of 20% to 90% by weight of the cathode active layer.

  Non-limiting examples of liquid media (eg, solvents) suitable for the preparation of the cathode (and other components of the cells described herein) include aqueous liquids, non-aqueous liquids, and mixtures thereof. Can be mentioned. In some embodiments, liquids such as water, methanol, ethanol, isopropanol, propanol, butanol, tetrahydrofuran, dimethoxyethane, acetone, toluene, xylene, acetonitrile, cyclohexane, and mixtures thereof can be used. Of course, other suitable solvents may also be used if desired.

  The positive electrode layer can be adjusted by methods known in the art. For example, one suitable method includes: (a) dispersing or suspending the electroactive sulfur-containing material described herein in a liquid medium; (b) optionally, the step (a A step of adding a conductive filler and / or a binder to the mixture of); (c) a step of mixing the composition obtained from step (b) to disperse the electroactive sulfur-containing material; Casting the composition obtained from step (c) onto a suitable substrate; and (e) removing some or all of the liquid from the composition obtained from step (d); Forming a cathode active layer.

  Suitable negative electrode materials for the anode active layer described herein include lithium metal (eg, lithium deposited on a lithium foil and conductive substrate, and lithium alloys (eg, lithium-aluminum alloys). And lithium-tin alloys), although these are preferred negative electrode materials, the current collector can be used with other cell chemistries.

  Methods for depositing negative electrode materials (eg, alkali metal anodes (eg, lithium)) on substrates include methods such as thermal evaporation, sputtering, jet vapor deposition, and laser ablation. Can be mentioned. Alternatively, if the anode includes lithium foil, or lithium foil and a substrate, they can be laminated together by a lamination process known in the art to form the anode.

  The positive and / or negative electrodes are suitable electrolytes (eg, US Provisional Patent Application No. 60 / 872,939 (filed Dec. 4, 2006, entitled “Separation of Electrolytes”, Mikhaylik et al.)) Optionally, one or more layers may be included that interact conveniently with those described in (1), which is incorporated herein by reference in its entirety.

  The electrolytes used in electrochemical cells or battery cells can function as a medium for ion storage and transport, and in the special case of solid and gel electrolytes, these materials are the anode and the cathode. It can further function as a separator. Any liquid, solid, or gel material capable of storing and transporting ions is such that the material is electrochemically and chemically non-reactive with respect to the anode and the cathode and between the anode and the cathode. It can be used as long as it facilitates transport of ions (eg, lithium ions). The electrolyte is electronically non-conductive to prevent a short circuit between the anode and the cathode.

  The electrolyte can include one or more ionic electrolyte salts and one or more liquid electrolyte solvents, gel polymer materials, or polymer materials to provide ionic conductivity. Suitable non-aqueous electrolytes may include organic electrolytes that include one or more materials selected from the group consisting of liquid electrolytes, gel polymer electrolytes, and solid polymer electrolytes. Examples of non-aqueous electrolytes for lithium batteries are described in Lithium Batteries, New Materials, Developments and Perspectives, Chapter 4, pp. 137-165, Elsevier, Amsterdam (1994). Examples of gel polymer electrolytes and solid polymer electrolytes are described in Lithium Batteries, New Materials, Developments and Perspectives, Chapter 3, pp. 93-136, Elsevier, Amsterdam (1994). Heterogeneous electrolyte compositions that can be used in the batteries described herein are described in US Provisional Patent Application No. 60 / 872,939 (filed Dec. 4, 2006). Examples of useful non-aqueous liquid electrolyte solvents include non-aqueous organic solvents (eg, N-methylacetamide, acetonitrile, acetal, ketal, ester, carbonate, sulfone, sulfite, sulfolane, aliphatic ether, cyclic ether. , Glyme, polyether, phosphate ester, siloxane, dioxolane, N-alkylpyrrolidone, substituted forms of the foregoing, and blends thereof, and fluorinated derivatives of the foregoing may also be used in liquid electrolytes. Useful as a solvent.

  In some cases, an aqueous solvent can be used as an electrolyte for a lithium battery. The aqueous solvent can include water, which can include other components (eg, ionic salts). As noted above, in some embodiments, the electrolyte may include a species such as lithium hydroxide, or other species that make the electrolyte basic to reduce the concentration of hydrogen ions in the electrolyte. .

  Liquid electrolyte solvents can also be useful as plasticizers for gel polymer electrolytes, ie, electrolytes that include one or more polymers forming a semi-solid network. Examples of useful gel polymer electrolytes include polyethylene oxide, polypropylene oxide, polyacrylonitrile, polysiloxane, polyimide, polyphosphazene, polyether, sulfonated polyimide, perfluorinated membrane (NAFION resin), polydivinyl polyethylene glycol, polyethylene glycol One or more selected from the group consisting of diacrylate, polyethylene glycol dimethacrylate, the aforementioned derivatives, the aforementioned copolymers, the aforementioned cross-linked and network structures, and the aforementioned blends, and optionally one or more plasticizers. Although the thing containing this polymer is mentioned, It is not limited to these. In some embodiments, the gel polymer electrolyte is between 10-20%, between 20-40%, between 60-70%, between 70-80%, between 80-90% by volume. Or between 90 and 95% heterogeneous electrolyte.

  In some embodiments, one or more solid polymers can be used to form the electrolyte. Examples of useful solid polymer electrolytes include polyethers, polyethylene oxide, polypropylene oxide, polyimides, polyphosphazenes, polyacrylonitriles, polysiloxanes, the aforementioned derivatives, the aforementioned copolymers, the aforementioned crosslinked and network structures, and the aforementioned blends. Examples include, but are not limited to, those containing one or more polymers selected from the group consisting of:

  In addition to polymers known in the art for the formation of electrolyte solvents, gelling agents, and electrolytes, the electrolyte further includes one or more ionic electrolyte salts known in the art to increase ionic conductivity. obtain.

Examples of ionic electrolyte salts for use in the electrolyte of the present invention include LiSCN, LiBr, LiI, LiClO ₄ , LiAsF ₆ , LiSO ₃ CF ₃ , LiSO ₃ CH ₃ , LiBF ₄ , LiB (Ph) ₄ , LiPF. ₆ , LiC (SO ₂ CF ₃ ) ₃ , and LiN (SO ₂ CF ₃ ) ₂ . Other electrolyte salts that may be useful include lithium polysulfide (Li ₂ S _x ), and lithium salt of organic ionic polysulfide (LiS _x R) _n, where x is an integer from 1 to 20 and n is , R is an organic group), and those described in US Pat. No. 5,538,812 (Lee et al.).

  In some embodiments, the electrochemical cell can further include a separator sandwiched between the cathode and the anode. The separator is a solid, non-conductive or insulating material that separates or insulates the anode and the cathode from each other, prevents short circuits, and allows the transport of ions between the anode and the cathode. obtain.

  The pores of the separator can be partially or substantially filled with electrolyte. The separator can be supplied as a porous self-supporting film that sandwiches the anode and cathode during the manufacture of the cell. Alternatively, the porous separator layer can be one of the above electrodes as described, for example, in PCT Publication No. WO 99/33125 (Carlson et al.) And US Pat. No. 5,194,341 (Bagley et al.). It can be applied directly to the surface.

  Various separator materials are known in the art. Examples of suitable solid porous separator materials include, but are not limited to, polyolefins (eg, polyethylene and polypropylene), glass fiber filter paper, and ceramic materials. Further examples of separators and separator materials suitable for use in the present invention include microporous xerogel layers (eg, microporous pseudo-boehmite layers), which are disclosed in US Pat. As described in US Pat. Nos. 6,153,337 and 6,306,545 (commonly assigned by Carlson et al.), As a self-supporting film or directly on one of the above electrodes Can be applied either by: Solid electrolytes and gel electrolytes can also function as separators in addition to their electrolyte function.

  The drawings accompanying this disclosure are only schematic and illustrate a substantially flat battery arrangement. It should be understood that any electrochemical cell arrangement can be constructed using the principles of the present invention in any configuration. For example, a further arrangement may be found in US patent application Ser. No. 11 / 400,025 (filed Apr. 6, 2006, entitled “Electrode Protection in both Aqueous and Non-Aqueous Electrochemical cells, Inclusion Rechargeable A et al.”). ), Which is hereby incorporated by reference in its entirety.

  While several embodiments of the present invention have been described and illustrated herein, those skilled in the art will perform the functions described herein and / or out of the results and / or advantages. Various other means and / or structures are readily recalled to obtain one or more, and each such variation and / or modification is considered to be within the scope of the invention. More generally, those skilled in the art will understand that all parameters, dimensions, materials and configurations described herein are illustrative and that the actual parameters, dimensions, materials and / or configurations are It will be readily appreciated that the teachings of the present invention depend on the particular application used. Those skilled in the art will recognize many equivalents to the specific embodiments of the invention described herein or may be ascertained using only routine experimentation. Accordingly, the foregoing embodiments have been shown by way of example only and the present invention may be practiced otherwise than as specifically described and claimed within the scope of the appended claims and their equivalents. It should be understood that it can be implemented. The present invention is directed to each individual feature, system, article, material, kit, and / or method described herein. Further, any combination of two or more such features, systems, articles, materials, kits, and / or methods is mutually inconsistent with such features, systems, articles, materials, kits, and / or methods. Otherwise, it is within the scope of the present invention.

  The indefinite articles “a” and “an” as used in the specification and claims refer to “at least 1” unless expressly stated otherwise. It should be understood to mean "one".

  The phrase “and / or” as used herein and in the claims refers to “any or both” of the elements so coupled, ie, in some cases, connective. It should be understood to mean elements that are present in, and in other cases, elements that are present in a disjunctive manner. Other elements are specifically identified by “and / or” clauses, as appropriate, whether or not related to what is specifically identified, unless explicitly stated otherwise There may be other elements than Thus, as a non-limiting example, a reference to “A and / or B” when used in connection with an open language such as “includes”, in one embodiment, is A and no B (required) In other embodiments, with B, without A (including elements other than A as needed); in yet another embodiment, both A and B are present (required) Depending on the other elements);

  As used herein in the specification and in the claims, “or or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” is intended to be inclusive, ie, interpreted as at least one inclusion, but similarly the number of elements or It shall be construed as including more than one of the lists and, where appropriate, including items not listed. However, the terms clearly indicated otherwise (eg, “only one of” or “exactly one of”), or “when used in the claims” "Refers to the inclusion of exactly one element in the number or list of elements. In general, the term “or” as used herein refers to an exclusive term (eg, “any one” or “one of”, “only one of” or “ If preceded by “exactly one of”), it is to be interpreted as indicating an exclusive option (ie, “one or the other, not both”). “Consisting essentially of” shall have its ordinary meaning as used in the claims, as used in the field of patent law.

  As used herein and in the claims, the phrase “at least one” refers to a list of one or more elements and is selected from any one or more of the elements in the list of elements. Does not necessarily include at least one of each and every element specifically recited in the list of elements, but means at least one element does not exclude any combination of elements in the list of elements It should be understood that This definition is also specifically identified in the list of elements to which an element refers, regardless of whether the phrase “at least one” is related to or not related to the specifically identified element. Allows it to exist outside of elements. Thus, as a non-limiting example, “at least one of A and B” (or equivalently, “at least one of A or B”, or equivalently, “A and / or At least one of B "), in one embodiment, includes at least one A (optionally including more than one A) and no B (and optionally other than B) In another embodiment, at least one B (optionally including more than one B), and A is absent (and optionally includes elements other than A); In yet another embodiment, at least one A (optionally including more than one A) and at least one B (optionally including more than one B) (and optionally) , Including other elements) Mention may be made to such.

  In the claims and in the specification above, all connected phrases (eg, “comprising”, “including”, “carrying”, “ It should be understood that “having”, “containing”, “involving”, “holding” and the like are open systems. It is to be understood that it means, but not limited to, that is, but consists essentially of the connected phrases “consisting of” and “consisting of ( consisting essentially of) " As described in Section 2111.03, each is a closed or semi-closed connection phrase.

Example 1
The following example describes the formation of a filler material within the pores of a porous carbon material, according to one embodiment of the present invention.

  The filler material was formed on the porous carbon material by thermal cycling to repeatedly dissolve and precipitate the filler material in the pores of the porous carbon material. In this example, ammonium carbonate or ammonium bicarbonate was used as the filler material. Because each exhibits a positive temperature solubility gradient in water, i.e., the solubility of the ammonium carbonate or ammonium bicarbonate in water increases with increasing temperature and decreases with decreasing temperature. . FIG. 4 shows graphs of (a) ammonium bicarbonate solubility in water as a function of temperature, and (b) ammonium bicarbonate thermal cycling diagram in water.

  According to the thermal cycling diagram in FIG. 4B, an aqueous solution of ammonium carbonate or ammonium bicarbonate was brought into contact with the porous carbon material and heated to about 50 ° C. to fill the carbon pores with the solution. The solution temperature was then reduced to approximately 0 ° C. and the filler material was precipitated in the carbon pores. The above process was repeated 2-3 times to deposit the desired amount of filler material in the pores. A filler content of about 75-90% by weight with respect to the porous carbon material was achieved.

(Example 2)
In the following examples, an electrochemical cell was prepared using a filler material and a soluble binder material as described herein, and its sulfur specific capacitance was measured.

A composite containing XE2 carbon (11.1 wt%) and ammonium bicarbonate (88.9 wt%) was prepared by adding XE2 to a saturated solution of ammonium bicarbonate above 50 ° C. The mixture was then cooled to 0 ° C. and NH ₄ HCO ₃ was precipitated into the carbon pores. The precipitated NH ₄ HCO ₃ was filtered to provide the XE2 composite, which was then washed with ethanol. The composite (21.37 g) was then mixed with 33.3 g of a 3 wt% EPDMN binder solution in hexane and 6.63 g of sulfur powder. An additional 35.3 g of hexane was added to the slurry mixture, which was then milled with stainless steel balls in a vial for 40 minutes.

To coat the cathode, the milled slurry mixture was manually drawn onto a carbon-coated 12 micron Al substrate (AL Rexam primer), and the coated cathode was placed in an oven at + 70 ° C. for 1 Dry over time to remove the solvent and filler material. The resulting composite contained sulfur (66.3% by weight), XE2 (23.7% by weight), and EPDMN (10% by weight). The cathode had good adhesion and adhesion. The sulfur coated load was 5.18 mg / cm ² .

An electrochemical cell was then assembled using the coated cathode and 6 mil Li foil, 9 m Tonen separator and 1.02 g electrolyte as the electrode (active area 33 cm ² ). Depending on the particular experiment, the electrolyte can contain 1,3-dioxolane (DOL) and 1-methoxy-2-ethoxyethane (MEE) with various and small amounts of CF ₃ SO ₂ ) ₂ NLi and LiNO ₃ Mainly included. In one particular embodiment, the electrolyte is 69.16 wt% DOL, 21.34 wt% MEE, 6.72 _{wt% (CF 3 SO 2) 2} NLi, and 2.77 wt% LiNO ₃ contains It was out. The cell was cycled on discharging to 15 mA 1.7V and charging to 15 mA 2.5V. The sulfur specific electric capacity in the fifth cycle was 1048 mAh / g, and in the 40th cycle, it was 1011 mAh / g.

As a control experiment, the same electrochemical cell was used, except that pure XE2 without filler was used instead of XE2-ammonium bicarbonate composite to prepare the slurry and coat the cathode. Prepared as above. The cathode coating had very poor adhesion and adhesion to the XE2 substrate. The cathode had a sulfur load of 2.17 mg / cm ² and was assembled into an electrochemical cell as described above. The sulfur specific electric capacity was 937 mAh / g in the fifth cycle and decreased to 845 mAh / g in the 40th cycle.

Example 3
In the following examples, an electrochemical cell was prepared using a filler material and a soluble binder material as described herein, and its sulfur specific capacity was evaluated.

An XE2-ammonium carbonate (NH ₄ ) ₂ CO ₃ composite having an XE2 content of 15.7 wt% and an ammonium bicarbonate content of 84.3% wt was prepared according to the method described in Example 2. The composite was then mixed with 33.3 g of a 3 wt% EPDMN binder solution in hexane and 6.63 g of sulfur powder. The XE2- (NH ₄ ) ₂ CO ₃ composite was then treated with 9.97 wt% sulfur, 22.06 wt% XE2- (NH ₄ ) ₂ CO ₃ composite, as described in Example 2. Coated using a milled hexane slurry containing and 1.5 wt% EPMN soluble binder. The coated cathode was dried in an oven at + 70 ° C. for 1 hour to remove the solvent and filler material. The obtained composite material contained sulfur (66.3% by weight), XE2 (23.7% by weight), and EPDMN (10% by weight). The cathode had good adhesion and adhesion. The sulfur coated load was 4.3 mg / cm ² .

  An electrochemical cell was then assembled as in Example 2 using the coated cathode described above. The cell was cycled under conditions similar to Example 2. The sulfur specific electric capacity in the fifth cycle was 1214 mAh / g.

  As a control experiment, the same electrochemical cell was prepared except that pure XE2 without filler was used instead of XE2-ammonium bicarbonate composite, except that the slurry was prepared and the cathode was coated. did. The cathode coating has a low sulfur load and very poor adhesion and adhesion to the XE2 substrate, and when assembled into an electrochemical cell, similar to the control experiment described in Example 2 Insufficient sulfur specific capacity.

Example 4
In the following examples, an electrochemical cell was prepared using a filler material and a soluble binder material as described herein, and its sulfur specific capacity was evaluated.

An XE2-water composite having an XE2 content of 28.5 wt% and a water content of 71.5% was prepared by adding carbon to boiling water and cooling to a stir bar, room temperature. Then, the _{XE2-H 2} O composite, _{XE2-H 2} O composite of 9.97 g, 7.96 g of sulfur, of 40 g, 3 wt% EPDMN solution in hexane, and 10g of hexane were mill hexane The slurry mixture was used for coating. The coated cathode was dried in an oven at + 70 ° C. for 1 hour to remove the solvent, and then the filler material was removed at 100 ° C. for 1 hour. The obtained composite material contained sulfur (66.3% by weight), XE2 (23.7% by weight), and EPDMN (10% by weight). The cathode had good adhesion and adhesion. The sulfur coated load was 3.4 mg / cm ² .

  The electrochemical cell was then assembled and cycled as in Example 2. In the fifth cycle, the sulfur specific electric capacity was 1070 mAh / g, and in the 40th cycle, it was 947 mAh / g.

  As a control experiment, the same electrochemical cell was used as described above, except that pure XE2 without filler was used instead of XE2-water composite to prepare the slurry and coat the cathode. Prepared. The cathode coating has a low sulfur load and very poor adhesion and adhesion to the XE2 substrate, and when assembled into an electrochemical cell, similar to the control experiment described in Example 2 Insufficient sulfur specific capacity.

(Example 5)
In the following examples, the filler material was studied for its ability to protect carbon porosity and surface area.

  Porous XE2 carbon can be obtained using either (1) a slurry containing EPMN in hexane (eg, no filler material) or (2) a slurry containing ammonium bicarbonate filler material and EPMN in hexane. Coated as described in Example 2. The coated XE2 carbon is dried at room temperature, then heated to 70 ° C. to remove the solvent and filler material, and coated XE2 carbon with a 3: 1 carbon to binder weight ratio is obtained. Generated.

BET surface area measurements were made on the dried XE2 carbon sample. In the absence of binder, the XE2 carbon sample treated with hexane had a surface area of 977 m ² / g, while the unprotected XE2 carbon sample treated with the binder solution was 96 m ² / g. Shows reduced surface properties. The XE2-NH ₄ HCO ₃ composite material treated with the binder solution retained a surface area of 319 m ² / g.

  These measurements indicated that the filler material acts as a pore protector for the XE2 carbon sample.

(Example 6)
Two electrochemical cells A and B were prepared using the method described in Example 3. Cell A was cycled at a discharge current density of 0.5 mA / cm ² and a charge current density of 0.5 mA / cm ² . For cell B, a discharge current density of 0.5 mA / cm ² and a charge current density of 0.5 mA / cm ² were applied over the first 5 cycles. For the following three cycles of cell B, a discharge current density of 1.0 mA / cm ² and a charge current density of 0.5 mA / cm ² were applied.

FIG. 6 shows the specific capacitance as a function of the number of cycles in cell A and cell B. Cell A gave a specific capacity of 1160-1260 mAh / g, or 69-75% sulfur utilization for the first 8 cycles. Cell B provided a specific electrical capacity of 940 mAh / g, or 56% sulfur utilization at a discharge current density of 1.0 mA / cm ² .

(Example 7)
In the following examples, several electrochemical cells are prepared using a cathode prepared with a liquid filler material present on a porous substrate and a soluble binder material, as described herein. did. These electrochemical cells were then prepared using a cathode having a porous substrate and a soluble binder material, but having no liquid filler material applied on the porous substrate. Comparison with similar cells. The specific capacities of these electrochemical cells were compared at several discharge currents. The liquid filler used in this example was octane, and the filler was applied to the porous substrate using a saturation method similar to the technique described above.

  130 g of Vulcan carbon powder was placed in a metal sieve. The sieve mesh is small enough to maintain the carbon powder without material loss through the sieve. The sieve was then placed in a glass desiccator and hung on a few grams of desiccant material. The vessel was then degassed by a conventional mechanical roughing pump; the vessel was purged of gas by this method for several minutes, and the carbon powder was left in the degassed vessel overnight. It was allowed to stand (about 16 hours). Next, the desiccator was opened in a dry atmosphere, and the carbon-containing sheave was taken out. The desiccant was replaced with 70 g octane at room temperature and a magnetic stirrer bar was placed at the bottom of the vessel. The carbon in the sieve was replaced in the desiccator and the vessel was degassed again using a mechanical coarse pump for several minutes. Once the vessel was degassed, it was placed on a magnetic stirring / heating plate and the octane was stirred at the slowest setting. The carbon was then allowed to stand and the octane was absorbed from the atmosphere for 2 days. On the third day, the heating element in the stirring / heating plate was turned on and the temperature of the vessel was raised to 80 ° C. to increase the rate of octane absorption from the vapor. Once there was no visible liquid at the bottom of the desiccator, the carbon was removed and used appropriately to prepare the cathode slurry.

The octane-filled carbon was mixed with a solution of 2156.3 g solvent containing 47.5 wt% water, 34.4 g PVOH, and 178.8 g sulfur, which was milled for 25 minutes. Once the carbons were mixed with this solution, they were milled together for an additional 5 minutes to make a 13.75% solid slurry. The slurry was coated onto the substrate using an atmospheric slot die coater and then dried at about 100 ° C. for about 3 minutes using an IR oven. The resulting dry cathode contained 52 wt% sulfur, 38 wt% Vulcan carbon and 10 wt% PVOH. The cathode load was 1.85 mg / cm ² . Control cathodes were prepared as described above except that they were received from the material supplier using Vulcan carbon as the slurry. The slurry prepared for the control cathode was subjected to the same mill procedure, mixing procedure, and coating procedure as described above.

An electrochemical cell was fabricated using both cathodes described above, 3 mil Li foil facing each other, and using a 9 μm Tonen separator. Some electrochemical cells were prepared with a liquid filler and some were prepared without a liquid filler. Several experiments were performed where various electrochemical cells were prepared using varying conditions of the electrolyte. The cell is 7.6 g containing mainly 1,3 dioxolane (DOL) and dimethoxyethane (DME) with limited and varying amounts of Liimide, LiNO ₃ , guanidine nitrate and pyridine nitrate at different specific conditions. Each was filled with an electrolyte solution. Thirty electrochemical cells of similar composition were tested in 6 groups as shown in the table below. Each group of five cells was cycled with a discharge current of either 500 mA, 2.2 A, or 4.4 A from 2.5 V to 1.7 V, followed by charging to 2.5 V at 315 mA. .

FIG. 7 shows (a) 500 mA (group 1), (b) 2.2A (group 2), and (c) 4 as a function of the number of cycles for cells prepared using octane as the liquid filler. For a group of cells prepared at a discharge current of .4 A (group 3) and without octane as a liquid filler, (d) 500 mA (group 4), (e) 2.2 A (group 5), and (F) A plot of average specific capacitance at a discharge current of 4.4A (Group 6). Cells made with cathodes prepared using the liquid filler system applied to the porous substrate had discharge currents of 500 mA, 2.2 A and 4.4 A, respectively, and 1087 mAh at the 10th discharge. / G _sulfur specific capacity, 1005 mAh / g _sulfur specific capacity, and 920 mAh / g _sulfur specific capacity. Cells made from cathodes prepared without the liquid filler system applied to the porous substrate had discharge currents of 500 mA, 2.2 A and 4.4 A, respectively, and 1089 mAh / g in the 10th discharge. _{It had a sulfur} specific capacity, a 929 mAh / g _sulfur specific capacity, and a 717 mAh / g _sulfur specific capacity. As shown in FIG. 7, a cell prepared using octane as the liquid filler has improved performance at high discharge currents compared to essentially the same cell prepared without the liquid filler. Indicated.

Claims (18)

A method for forming an electrode comprising:
Forming a filler material on the surface of the porous material and / or in the pores , wherein the porous material comprises porous carbon;
After forming the filler material on the surface of the porous material and / or within the pores, comprising the steps of forming an electrode material on the at least a portion of the porous material, wherein the electrode material Comprising an active electrode species and a binder material; and removing the filler material from the porous material, thereby forming the electrode;
Including the method. The binder material and the active electrode species are applied to the porous material from a mixture comprising the binder material, the active electrode species, and a fluid carrier, wherein the binder material is at least partially in the fluid carrier. The method of claim 1, which is soluble in nature. The method of claim 1, wherein the filler material is a hydrophilic material and the binder material is soluble in a hydrophobic solvent. The method of claim 1, wherein the filler material is a hydrophobic material and the binder material is soluble in a hydrophilic solvent. The method of claim 1, wherein the binder material is provided in a solvent in which the binder material is substantially soluble. The method of claim 1, wherein the removing includes heating the porous material. The method of claim 1, further comprising forming a polymer material on at least a portion of the porous material prior to forming the filler material. The method of claim 7 , wherein the polymeric material is a poly (ethylene glycol) coating. The method of claim 1, wherein the filler material is a solid. The method of claim 1, wherein the filler material is a liquid. The method of claim 1, wherein the filler material is octane, ammonium carbonate, or ammonium bicarbonate. The method of claim 1, wherein the binder material is a polymeric material. The method of claim 1, wherein the binder material is poly (ethylene-co-propylene-co-5-methylene-2-norbornene) (EPMN). The method of claim 1, wherein the active electrode species is sulfur. The method of claim 14 , wherein the electrode has a sulfur load of at least 1.5 mg / cm ² . The method of claim 14 , wherein the electrode has a sulfur load of at least 2.5 mg / cm ² . The method of claim 14 , wherein the electrode has a sulfur load of at least 5.0 mg / cm ² . A method for forming an electrode comprising:
Contacting a porous material comprising porous carbon with a filler solution comprising a filler material such that the filler material forms a coating on the surface of the porous material and / or in the pores ; Producing a coated porous material of:
A porous material coated the first, an electrode material comprising an active electrode species and a binder material, the electrode material, the contacted to form a coating on at least a portion of the porous material Producing a second coated porous material; and removing at least some of the filler material from the second coated porous material, thereby forming the electrode;
Including the method.